Why not? There is no free will, and no accountability, and the desire for hurtful people to suffer is just a moralistic impulse founded on a misunderstanding of the human condition. One might argue: He was bad because he caused suffering, and this assumes that suffering is bad, i.e. that the less suffering the better, so hopefully his death represents a diminishing of suffering -- but that would require that he rest in peace. It is confusion to think that pain negates pain: it compounds it.